Drill



Patented Nov. 17, 1.942

DRILL Wilhelm SchWenecke, Kothen, Germany; vested inthe Alien Property Custodian Appication July 25, 1940,4Seria1,No. 3f i7,495 In Germany March 13, 1939 1-9 Claims.

This invention relates to a drill andreiers vmore particularly to a boring or -drilling Mtool -having an automatic eed movement and a quick return movement.

An object of the present invention is the provision of a boring or drilling tool having an automatic feed movement and quick return movement and so constructed that it can be used for a great variety of different purposes and can be set to operate in any desired direction.

Another object is the provision of a boring tool of such construction that a plurality of these tools can be conveniently combined to constitute a single multi-spindle drilling machine.

A further object is the provision of a boring tool all of the operative movements of which take place automatically.

A still further object of the `present invention is the provision of a driving device for a boring tool which makes it possible to adjust the position of the tool by hand and at the same time causes the tool to carry out automatically its feed movement and `its quick return movement.

Yet another object is the provision of a device which is switched on automatically to cause a boring tool to carry out a quick return movement after its feed movement has been brought to an end, while at the end of the return movement said device and the entire drive are automatically switched oli.

Another object of the present invention is the provision of a boring tool which is constructed as compactly as possible particularly as far as its Width is concerned, so that a plurality of these tools when operating simultaneously, can drill holes situated at a small distance one from the other.

A further object of the present invention is the provision of a drill having driving means and a device for switching and steering the drill, which are so constructed that the drill can be conveniently adjusted and switched on and oi in many different ways and that it requires little space in directions transverse to the direction of its operation.

In accomplishing the above and other objects of the present invention, it Was found advisable to provide a drill having a feed drive which consists oi two interconnected driving elements rotating with different speeds and situated within the spindle of the drill. The drill spindle is preferably eccentrically located in the casing of the tool. The switching and steering means for the feed movement are situated directly behind the l drill spindle and are so mounted upon a front surface of the tool casing that they do not require more space in the transverse direction than is necessary for the other parts of the tool. The casing of the tool may loe-of rectangular form and provided with smooth outer surfaces, so that the .tool can berconven-iently set to operate in vertical, horizontal or any inclined positions,`and so that many of such tools can be convenientlycombined intoa multiple-spindle unit.

f lIn raccordance with the presentinvention, two powerv transmitting devices are included in the ieed drive of the tool. One of these devices is used vto drive a feed spindle which .actuates .the drill spindle. The other device is .used for operating a driving element which is so connected with the drillspindle that 'it can rotate relatively thereto but cannot move longitudinally thereof. This driving element cooperates with the feed spindle. The two power transmittingdevices rrotate with 4diierentspeeds,.and the difference between the twospeeds determines the speed of the feed movement of the drill spindle.

Furthermore, in accordance with the present invention, Ythe difference in the ratios of the two i `power-transmitting devices is so selected `that the reed spindle `rotates with a speed whiohis greater than that of the driving element .cooperating therewith and connected with the drill spindle. Thus `.the guick return movement of the drill spindle Vis accomplished by a comparatively simple arrangement'.

The present invention is also concerned with the transmission of the drive for the feed spindle and for `the driving element cooperating therewith to the drill lspindle which is moved axially with different velocities, with the interruption of this drive, With means for actuating vthe drill spindle, and with the switching andY steering of VFigure 3 is another sectional view of a detail;

and

Figure 4 is a sectional view of a detail amplifying Figure 1.

Figure 5 shows the switching mechanism of the drill in longitudinal section.

Figure 1 shows a shaft or tool spindle I, the lower end of which carries a drill steel not shown in the drawing. The tool spindle I is rotatably mounted in a casing 2 of rectangular cross-section and is located eccentrically in relation to the cross-section.

The drive for the tool spindle I includes a pulley 4 which is firmly connected with a tube 3. A belt 4a embraces the pulley 4 and is actuated by the main drive of the boring machine which is not illustrated in the drawing. The belt 4a passes through an opening 2c provided in the casing 2.

Another opening 2d is provided in the casing 2 opposite the opening 2c, so that any of the sides of the drill may be directed toward the main drive.

The tube 3 is so connected with the tool spindle I that a rotation of the tube 3 is transmitted to the tube spindle I, while the latter is movable longitudinally in relation to the tube 3. 'Ihis is achieved by a spline shaft gear 5 which transmits the turning movement of the tube 3 to the tool spindle I.

A driving shaft 6 extends parallel to the axis of the tool spindle I in the casing 2. One end of the shaft 6 carries a gear I meshing with aV toothed crown 8 integral with the tube 3.

The opposite end of the shaft B carries the element 9 of a disc clutch 9, I9. The other clutch element I is rigidly connected with a hollow shaft II which encloses the shaft 6 and which is also mounted in the casing 2.

The hollow shaft II is provided with elongated teeth I2 extending over the major part of the shaft. The length of the teeth is determined by the extent of the feed movement of the spindle I.

A gear I3 meshes with the teeth I2 of the shaft I I and is firmly connected with a nut i4 having inner screw threads which engage the outer screw threads of a threaded spindle Ib. The threaded spindle I is situated within a bore IS of the tool spindle I.

The nut I4 is so mounted in the hub of a guiding piston I I4 that it can rotate relatively to the piston but cannot move longitudinally thereof.

The piston I I4 is situated within a guiding cylinder II5 which encloses the tool spindle I. A sleeve IIB is rmly connected with the piston II4 and with the tool spindle I, and is used to hold the piston I I4 in the tool spindle I. The shaft 6 is situated within a cut out portion provided in the cylinder H5.

The threaded spindle I5 is so mounted in a transverse inner wall 2a and the upper front wall 2b of the casing 2 that it can rotate relatively to these walls but cannot move longitudinally thereof.

In addition to the teeth I2 the hollow shaft I I also carries a gear I1 meshing with a gear wheel I3 which is loosely mounted upon the spindle I5.

The hub of the gear wheel I8 is firmly connected with the element I9 of a coupling I9, 29. The other element of this coupling constitutes a sleeve which is so keyed upon the spindle I5 that it cannot rotate relatively thereto but is movable longitudinally of the spindle I5.

A strong coiled spring 22 presses with its one end against a toothed collar 2i. The opposite end of the spring 22 is pressedagainst/a ring 23 which is so keyed upon the spindle I5 that it cannot rotate relatively thereto but can be adjusted in the longitudinal direction of the spindle by threaded nut rings or the like.

A ring 24 having inner screw threads is screwed upon the spindle I a portion of which is provided with outer screw threads. Therefore, the ring 24 which participates in the feed movement of the spindle can be adjusted and shifted longitudinally of the spindle.

The ring 24 carries a ring 26 which is supported by ball bearings in the ring 24. In the course of the feed movement of the spindle I and the ring 24, the ring 26 will strike the surface 25 of the casing 2. The device which causes the tool spindle I to carry out its various movements in the required sequence, is situated in the front or head portion of the casing directly behind the spindle I and is so Vconstructed that it does not occupy more space in directions transverse to the longitudinal direction of the spindle I than all the other parts of the tool.'

The object of this device is to switch on and off the coupling 9, I0 for the feed drive and the coupling I9. 29 for the threaded spindle I5 while the tool spindle i is operated, in a manner which will cause the spindle I to carry out the necessary movements automatically.

The device includes a two armed lever 3! which is rotatably mounted upon a pin 39 and is in engagement with an annular groove 33 provided in the coupling sleeve 29. The upper end 34 of the lever 3! is situated in the path of movement of a hook 36 constituting a part of an angular lever 35. The arm 37 of the lever 35 projects into an opening formed in a connecting rod 3S, so that the lever 35 is connected with the rod 32.. The rod 38 is engaged by la spring 39 and is so mounted in the casing 2 that it can move longitudinally therein.

The rod 33 includes a continuing narrower portion 49 which carries an adjustable abutment 4I. The abutment 4I is situated in the path of movement of the gear wheel I3 which moves longitudinally'along with the tool spindle I.

A second angular lever 42 is also pivotally mounted intermediate its ends in the casing 2. One end of the lever 42 carries a tooth 43 which is situated close to the gear wheel ZI mounted upon or integral with the sleeve 29.

The opposite end 44 of the angular lever 42 is adapted to engage a pin or bolt 45, which is mounted in the front wall 2b of the casing 2 and which is subjected to the pressure of a spring.

A two armed lever 4B is also pivotally mounted in the casing 2, as is shown more clearly in Figures l and 3 of the drawing.

One of the arms of the lever 46 is in engagement with an annular groove 47 of a sleeve 48 which is so mounted upon the coupling element 9 that it is movable longitudinally thereof.

The sleeve 43 cooperates with a plurality of levers 59 which are :adapted to engage the disc elements of the coupling 9, I0.

A link 49 shown best in Figures 2 and 3 is pivotally connected with that end of the lever 3i which is situated oppositethe projection 34. The other end of the link 49 is adapted to project into a `cavity 5I (Figure 3) provided in a pin 59 which while the opposite end of the spring 53 is connected to a projection constituting a part of the casing.

The pin is also connected with a link 54 carrying a 4coupling shoe 55 (Figures 3 and 5) which is adapted to engage the front surface of the coupling element I8. The coupling shoe 55 is also connected with a guiding pin 56 having inclined surfaces engaging a pin 51 which is mounted transversely in the casing 2 and which is subjected to the action of a spring, not shown in the drawing.

A cam disc or steeringV disc 60 is rotatably mounted in the head portion of the casing 2 close to the switching elements. The disc 6I) is provided with a projection or cam 6I which is situated upon the outer circumference of the disc 68 and is adapted to engage the projecting portion 62 of the link 49.

`Another portion of the outer circumference of the disc 60 carries teeth 63 which mesh with the teeth of a threaded rod or worm 64, shown in Figure 4. The rod 64 is so mounted in the head portion of the casing 2 that it can move in its longitudinal direction. A continuing narrower portion 65 of the rod 64 is situated within a tube 66 which is engaged by one end of a spring 61. The opposite end of the spring 61 presses against the inner wall 2a constituting a part of the lcasing 2 and shown in Figure l.

One end cf the tube 66 carries a ring 68 which is used as a stop and which is pressed against the casing by the spring 61, in the position shown in Figure 4.

The disc BI) has a hub having the form of a cam 69 which is adapted to engage a projection 'III` of the angular lever 35.

The disc 60 is also provided with two cut-out portions 1I and 12, the inner surfaces of which cooperate with rollers 13 and 14 mounted upon the levers 3l and 46, respectively. The cut-out portion 1I is provided with an inner cam surface 11 while the cut-out portion 12 has inner cam surfaces 16 and 18.

A handle 15 is firmly connected with the steering disc 6B and projects outside of the front surface of the casing 2.

The end 80 of the threaded spindle I5 also projects outside of the front surface of the casing 2 and may be provided with ka handle 8I by means of which the steering disc 60 may be operated to provide any desired axial adjustment of the tool spindle I in relation to the work piece after the feed drive has been switched off.

The operation of the spindle drive is as follows: The main drive of the machine which is not shown in the drawing, causes a rotation of the endless belt 4a which passes over the pulley 4. The rotation of the pulley 4 is transmitted to the tool spindle I by the gear 5 and is also transmitted by the toothed crown 8 which is integral with the pulley 3, by the gear 1 meshing with the crown 8, and by the shaft 6 carrying the gear 1, to the coupling sleeve 9 which is mounted upon the shaft 6. If the coupling 9, I0 is in its operative eng-aged position, then the rotation of the shaft 6 will be transmitted by the coupling 9, IU to the hollow shaft II.

The rotation of the shaft II is transmitted in the first place, by the teeth I2 to the gearwheel I3. In the second place, the rotation of the shaft II. is transmitted by the gear-wheel I1 to the gear-wheel I8.

If the coupling I9, 20 is in its operative engaged position, then the rotation of the gearwheell I8 will .be transmitted Vto the spindle I5. The gear-wheel' I3 will cause the Inut I4 to rotate inthe same direction.

The tool 'isV so constructed that the transmission ratio between the gears' I2 and I3 is greater than that between the gears I1 'and I8. Consequently, the-spindle I5 will rotate with greater speed than the nut I4. This results in an axial movement of the nut I4 in the direction of the feed movement which is indicated by the arrow :l: in Figure 1, provided that the pitch of the threads of the spindle I5 has been properly selected in relation to the direction of rotation of the tool spindle I.

Since the nut I4 is connected with the tool spindle I, the latter is moved in the direction of its longitudinal axis towardv the work piece. Thus, theV feed movement of the spindle I takes place.

rlrhis feed movement is brought to an end when the ring 26 which Ais mounted upon the spindle I by means of the ring 24 is caused to strike the surface 25 of the casing 2. The tool spindle I continues toyrotate after the engagement between the surf-ace 25 and the ring 26 hasv taken place. However, since the ring 26 is connected by ball bearingsrwith the ring 24, the rotation of the spindle I will merely cause a rolling frictional `movement between the ring 24 and the ring 26.

Thel force creating the feed movement of the tool spindle I thus nds a resistance which is greater than the tension of the spring `22 which is situated between the coupling I 9, 20 and the ring 23. The tension of the spring 22 is so selected that it can transmit only a turning movement of a predetermined value. This value is now exceeded and, therefore, the spring 22 will disengage the lcoupling I9, 20 which is provided with teeth having a corresponding inclination,

shifting the coupling element 20 out of its operative position and moving it axially. As a result of this disengagement of the coupling I9, 20, the operative connection between the gear I8 and the spindle I5 will be interrupted and the gear I8 will rotate loosely upon the spindle I5. Then the movement of the spindle I5 will be brought to an end. The spindle I5 will be locked by the lever 42, as will be described in detail hereinafter.

Since the nut I4 continues to carry out its rotary movement and since the spindle I5vis now immovable, the nut I4 will move axially upon the spindle I5 in a direction opposed to that of the arrow x. The tool spindle I which is connected with the nut I4, will move along with it and will carry out its return movement, since the transmission ratio between the gears I2 and I3` which remain in operative engagement is greater than the transmission ratio between the gears I1 and I8 which are now disconnected.

Since, on the one hand, the diierence between transmission ratio ofthe drive for the nut I4 and the transmission ratio of the drive for the spindle I5 has been purposely selected as small, while on the other hand the speed difference between the rotating spindle I5 and the immovable spindle I5 is very great, the return movement of the nut I4 and consequently, of the tool spindle I is considerably faster than the feed movement. Therefore, the described arrangement makes it possible'to achieve a quick return movement of the tool spindle I.

The operation of the switching devices is as follows: f i

the lever 3| which is in engagement with the element 29 to move into the position shown in Figure 2. The teeth of the collar 2| are then brought into engagement with the tooth -43 of the angular lever 42, so that the coupling sleeve 29 and, consequently, the threaded spindle I5 are prevented from rotating any further. The nut I4 which is driven by the gears IZand I3 is the sole element which continues to carry out a rotary movement and, dueto the selection y of the transmission ratiosof ,the-gears I2, I3 and Il, I8, the tool spindle I will carry out its return movement.

At the same time, the projection 34 of the lever 3| is moved below the hook 36 of the angular lever 35. The spring 39'ho1dsthe rod 38 and the lever 35` connected therewith in this position, which is shown in Figure 2. The coupling 9, I8 for the feed drive which, at that time, transmits the return movement, is placed simultaneously by the lever 3| in a position in Which itis ready to stop that return movement. This is accomplished by transmitting the swinging movement of the lever 3| to the link 49 and thereby causing the spring 53 to insert the pro- -jection 52 of the link 49 into the cut out portion 5| of the bolt 50. This connects the means actuating the coupling 9, I for the feed drive with the other switching means of the tool.

At the completion of the return movement of the tool spindle I, the gear wheel I3 strikes the abutment 4lmounted `upon the portion 49 of the rod 38 and thereafter, the abutment 4I and the rod 38 are moved along with the wheel I3, whereby the spring 39 is compressed. Thelengthwise movement of the rod 38 is transmitted to the angular lever 35 and the projection 34 of the lever 3| is freed by the hook 36 which is integral with the lever 35. l

Then, the lever 3| is moved by the spring 22 into its original position shown in Figure 1, and inthe course of this movement the lever 3| brings the coupling I9, 23 into its engaged position. Theopposite end of the angular lever 3| moves the link 49 and causes the projection 52 of this link to shiftV the sleeve 48. The sleeve 48 actuates the levers 58 and this results in the disengagement of the disc elements of the coupling 9, IIJ, so that thiscoupling is brought into its disengaged position. This operation is speeded by the brake or coupling Ashoe 55 which is movable along with the sleeve 48 and which is pressed by the spring actuated pin 51 against the front surface of the coupling element I3.

At the same time, the sleeve 48 swingsthe an gular lever 42 insuch manner that its tooth 43 is moved out of engagement with the toothed collar 2| which is integral with the sleeve 28. This frees Ythe threaded spindle I5 for rotation. It is now possible to turn the spindle I5 manually by means of a crank without switching off the drive, and therefore the tool spindle I can be shifted axially to adjust the position of the drill steel in relation to a new workpiece,

The steering disc 66 operates as follows:

If at the end of the return movement the steering disc 66 is turned manually in the direction of the arrow y shown:V in Figure 3, its cam 6| is brought' into engagement with the 4projecting portion 62 of the link 49. The cam 6I movesrthe` link 49 awayfrom the coupling pin 56, so that Athe projection 52 of the link 49 is brought out of engagement with the out out portion 5I of the pin 59. This frees the lever 46 and the sleeve 48 of the coupling elementV 9, so that the coupling 9, I9 can be switched on again.

When the disc 69 is turned still further in the same direction, namely inthe direction of the arrow y, the cam surface 'E6 of the cut out portion 'I2 will engage the roller 'I4 and will move this roller and the lever 46 in such manner, that the latter will swing the lever 58 vand thereby cause the disc coupling 9, I9 to move into an engaged position (Figs. 1 and 2). Then the gear elements I2, I3, and Il, I8 are switched on again into the drive of the machine.

In the course of the described rotation of the disc 69 in the direction of the arrow y, the earn 69 raises the angular lever 35 and then the hook 36 frees the upper end 34 of lever 3|, so that the spring 22 can press the coupling, element 26 against the coupling element i9 connected with the wheel i3. This causes the spindle l5 to participate again in the rotary movement and thus brings forth the automatic forward movement of the tool spindle I.

The described movements of the steering disc 66 has no effect upon the lever 3| carrying the roller T3. However, since the teeth 63 of the disc 68 mesh with the teeth of the rod 64 (Fig. 4), the rod 34 was moved in relation to the casing 2a and the spring 81 was compressed. If the 0perator releases the hand lever l5, the spring 6l will move the disc 66 back into its original position. The tube 66 and the portions 55 of the rod 64 are so dimensioned that the spring 6l moves the disc 66 only to its middle position which is shown in Fig. 3.

If the operator turns the lever 'I5 along with the disc 66 in the direction of the arrow e (Fig. 3) the cam surface 'il of the cut out portion 'II will engage the roller 'I3 of the lever 3|. The movement of the lever 3| will operate the coupling element 23 (Fig. 1) which is connected therewith, and will disengage the coupling I9, 26 and also lock the lever 3| by means of the hook 36 of the lever 35. This will disengage the gears i?, I8 and, as above stated, will switch on the mechanism causing the quick return movement of the tool spindle I.

If the disc 69 is turned still further in the direction of the arrow e, the cam surface 'i8 of the cut out portion 'I2`will engage the roller 'I4 carried by the lever 46 and will swing this lever causing the disengagement of the coupling 9, I0. Consequently, the entire driving mechanism for the tool spindle will be stopped.

Thereupon, the steering disc can be turned back into its original position by means of the hand lever l5 and by turning the lever l5 further in the direction of the arrow y, the feed drive can be switched on again.

Since the feed drive constructed in accordance with the present invention consists of two driving elements which are in engagement with each other and which rotate with diierent speeds, and since this drive is situated within the tool spindle, the dimensions of the tool in planes transverse to the direction of feed movement are very small. This makes it possible to use the tool in dierent location-s and for a large variety of purposes. Furthermore, the described construction makes it possible to carry out'the feed drive and -the quick return movementof the spindle with lthe lsmallest possible expenditure'of power.

Due to the small width of the tool, a large number of these tools may be used simultaneously to drill bore holes situated at short distances from each other, and, in general, a large number of the tools may be conveniently combined into a single machine. This combination of a plurality of tools into a single unit is alsofacilitated by the fact that the means switching and operating the feed drive are situated directly behind the tool spindle, namely, upon a front surface of the tool casing in the direction of the rearward continuation of the tool spindle.

All the driving elements as well as the steering and switching means of the tool are soselected, formed and arranged, that the tool casing may be of rectangular cross section and be provided with flat smooth side surfaces having no projecting portions or the like. This furthers the usefulness of the tool for a variety of purposes.

The fact that the axisof the tool spindle is eccentrically located in the casing makes it easier to combine several tools with different distances between their spindle axes into a single machine which can drill holes situated closely one to the other.

The feed drive constructed in accordancewith the principles of the present invention makes it possible to utilize a very small number of parts to provide an automatic feed movement and a return movement which is carried out with a much greater speed. The switching and-steering means which cause all the necessary operations of the tool, said operations being performed automatically to the greatest possible extent, require only a small number of parts, so that all these parts can be assembled within the smallest possible space and will carry out the switching and steering operations with very little danger of breakage or interruptions.

Furthermore, the switching and steering means are so selected, constructed and arranged that the tool requiresV very little attention or skill on the part of the operator in spite of the large number of switching and steering operations which are being performed, particularly since all switching operations are carried-out by manipulating asingle hand lever.

It is apparent that the speciiic illustrations shown above have been given by way of illustration and not by way of limitation and that the structures above described are subject to wide variation and modification, without departing from the scope or intent of the invention, all of which variations and modincations are to be include'd within the scope of the present invention. What is claimed is;

I. A drill, comprising a hollow tool spindle, two interengaging rotary driving elements` situated within said hollow tool spindle, one of said elements being operatively connected with said spindie, separate means connected with said driving elements for simultaneously rotating them with different speeds to cause said one element and said tool spindle to carryout a feed movement, and means stopping the rotation of the other one of said elements to, cause said one element and sai'd tool spindleto carry out va quick return movement. o

2. `A drill, comprising an elongated casing having a front portion, a hollow tool spindle situated eccentrically within said casing, two interen'gaging rotary driving elementssituated within said hollow tool spindle, one of said elements being operatively connected with said spindle, separate means connected with said. driving elements for simultaneously rotating `them with different speeds to cause said one element and said tool spindle to carry out a feed movement, means stopping the rotation of the other one of said elements to cause said one element and said tool spindle to carry out a quick return movement, and means situated within said casing directly behind said spindle adjacent to said front portion and connected with the iirst-mentioned and the second-mentioned means for causing the tool spindle to carry out automatically its quick return movement after the completion of the feed movement.

3. A drill, comprising a hollow tool spindle, two interengaging rotary driving elements situated within said hollow tool spindle, means connected with said tool spindle for rotating the same, driving means situated adjacent to said tool spindle and operatively connected therewith, one of said driving elements being operatively connected with said spindle, separate means operatively connected with said driving means and actuated thereby for simultaneously rotating said driving elements with different speeds to cause said one element and said tool spindle to carry out a feed movement, and means stopping the rotation of the other one of said elements to cause said one element and said tool spindle to carry outa quick return movement.

4. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a nut rotatably mounted in said tool spindle and meshing with said threaded spindle, said nut being movable longitudinally along with said tool spindie, separate gear drives connected with said threaded spindle and said nut for rotating said threaded spindle with a greater speed than said nut to cause said nut and said tool spindle to carry out a fe'ed movement, and means stopping the rotation of said threaded spindle to cause said nut and said tool spindle to carry out a quick return movement.

5. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, -a gear drive connected with said nut for rotating the same, another gear drive 4having a diierent transmission ratio and including a coupling connected with said threaded spindle; and means connected with said coupling for disengaging the same to stop the rotation of said threaded spindle and cause said nut and said tool spindle to carry out a quick return movement.

6. A drill, comprising a hollow tool spindle, a

- threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive connected with said nut for rotating the same, another gear drive having a different transmission ratio and including a coupling connected with said threaded spindle, and resilient means connected with said coupling and holding it in an engaged position, the difference in the transmission ratios of said drives causing 'said nut and said tool spindle to carry out a feed movement, the force of said resilient means being smaller than the force of said tool spindle in the course of its feed movement; and means causing said resilient means to disengage said coupling to stop the rotation of said threadedl spindle and cause said nut and said tool spindle to carry out a quick return movement.

7. A drill, comprising a hollow tool spindle,

two interengaging rotary driving elements situated within saidhollow tool spindle, one of said elements being operatively connected with said spindle, separate means connected with said driving elements for simultaneously rotating them with diierent speeds to cause said one element and said tool spindle to carry out a feed movement, a ring adjustably mountedupon said tool spindle, a casing enclosing said tool spindle and havinga portion extending in the path of movement Vof said ring to stop said feed movement, and means stopping the rotation of the other one of said elements to cause said one element and said tool spindle to carry out a quick return movement.

8. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected Vwith said nut, another gear drive having a diierent transmission ratio and including another coupling connected with said threaded spindle; and means operatively interconnecting the two couplings and adapted to be actuated by the movement of said tool spindle for disengaging the second-mentioned coupling to stop the rotation of said threaded spindle and cause said nut and said tool spindle to carry out a quick return movement.

9. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, another gear drive having a` different transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for disengaging the same to stop the rotation of said threaded spindle and cause said nut and said tool spindle to carry out a quick return movement, a hooked lever, and means connected with said hooked lever and operated during the return movement of the tool spindle for maintaining the secondmentioned coupling in its disengaged position.

10. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, another gear drive having a different transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for disengaging the same to stop the rotation of said threaded spindle and cause said nut and said tool spindle to carry out a quick return movement, a hooked lever, another lever having a projection adapted to be engaged by the hook of the rst-mentioned lever, means connected with the second-mentioned lever for maintaining the second-mentioned coupling in its disengaged position when the projection of the second-mentioned lever is engaged by the hook of the rstmentioned lever, and means actuated by said tool spindle for moving the first-mentioned lever away from the second-mentioned lever at the end of the return movement to bring the second-mentioned coupling into its engaged position.

11. A drill, comprising a hollow tool spindle, a

threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, another gear drive having a diierent transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for disengaging the same, and means connected with the last-mentioned means for preventing the rotation of said tool spindle when the second-mentioned coupling is disengaged.

12. A drill, comprising a hollow tool spindle, a threaded spindle within said toolspindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive in cluding a coupling connected with` said nut, another gear drive having ,a different transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling ior disengaging the same to cause said nut and said tool spindle to carry out a quick return movement, and means operatively connecting the last-mentioned means with the first-mentioned coupling when the second-mentioned coupling is disengaged.

13. A drill, comprising a hollow tool spindle, a

Y threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, means connected with said coupling for actuating the same, another gear drive having a diierent transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for actuating the same, and means interconnecting the means actuating the two couplings for disengaging the first-mentioned coupling when the second-mentioned coupling is moved into an engaged position.

14. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, means connected with said coupling for actuating the same, another gear drive having a diierent transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for actuating the same, means connected with the means actuating the second-mentioned coupling for preventing the rotation of said tool spindle when the second-mentioned coupling is disengaged, and means operatively Y connecting the last-mentioned means with the means actuating the rst-mentioned coupling to permit the rotation of said tool spindle when the rst-mentioned coupling is disengaged.

l5. A drill, comprising a'hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool'spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear driveincluding a coupling connected with said nut, means connected with said coupling for actuating the same, another gear drive having a different transmission ratio andV including another coupling connected with said threaded spindle, means connected with .the second-mentioned coupling for actuating the same, and manually operated means operatively connected with the means actuating the two couplings for operating the same.

16. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a r0- tary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, means connected with said coupling for actuating the same, another gear drive having a different transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for actuating the same, and a rotary steering disc having cam surfaces engaged by the means actuating the two couplings, whereby a rotation of said steering disc causes an engagement and disengagement of said couplings.

17. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, means connected with said coupling for actuating the same, another gear drive having a different transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for actuating the same, means operatively interconnecting the means actuating the two couplings, and manually operated means for interrupting the operative connection between the two couplings.

18. A drill, comprising a hollow tool spindle, a threaded spindle within said tool spindle, a rotary nut connected with said tool spindle and situated within the tool spindle, said threaded spindle meshing with said nut, a gear drive including a coupling connected with said nut, means connected with said coupling for actuating the same, another gear drive having a different transmission ratio and including another coupling connected with said threaded spindle, means connected with the second-mentioned coupling for actuating the same, a steering disc having cam surfaces engaged by the means actuating the two couplings, means connected with said disc for manually turning the same to cause an engagement and disengagement of said couplings, and resilient means connected with said disc for returning it to a neutral position.

19. A drill, comprising a hollow tool spindle, two interengaging rotary driving elements situated within said hollow tool spindle, one of said elements being operatively connected with said spindle, separate means connected with said driving elements for simultaneously rotating them with different speeds to cause said one element and said tool spindle to carry out a feed movement, means stopping the rotation of the other one of said elements to cause said one element and said tool spindle to carry out a quick return movement, a casing enclosing said tool spindle and having a plurality of openings formed therein, and means extending through at least some of said openings and engaging said tool spindle for rotating the same.

W'ILHELM SCHWENECKE. 

